BLE connection processing with nRF5340 Audio - 2

RE: BLE connection processing with nRF5340 Audio - 2

SNJY — Fri, 21 Mar 2025 22:22:26 GMT

An update on this,

I was able to add custom string to one of the data types and append it to the advertisement packet. I did this by inserting the same information in the unicast_server_adv_populate() function using bt_mgmt_adv_buffer_put. I was under the assumption that adding the data in the main.c/ext_adv_populate() would do the trick but adding it to unicast_server.c/unicast_server_adv_populate() made it work.

int unicast_server_adv_populate(struct bt_data *adv_buf, uint8_t adv_buf_vacant)
{
.
.
.


size_t brdcast_name_size = strlen(CUSTOM_NAME);

ret = bt_mgmt_adv_buffer_put(adv_buf, &adv_buf_cnt, adv_buf_vacant,
			     brdcast_name_size, BT_DATA_BROADCAST_NAME,
			     (char *)CUSTOM_NAME);
if (ret) {
	return ret;
}


.
.
.
}

Let me know if there is a better way.

RE: BLE connection processing with nRF5340 Audio - 2

SNJY — Fri, 21 Mar 2025 09:34:06 GMT

Hi Amanda,

I was able to partially implement what i was aiming for. But I am stuck at something related and is required for my implementation.

Since i have multiple peripherals, i have resorted to pairing and have removed the bonding process for now. I am implementing scan filters on the gateway to control which specific peripherals to connect to.

For this implementation, i want to add a custom string to the advertisement packet of the peripheral which i can look for on the central side. In the unicast server sample, the advertisement packets are populated with uuids for a couple of services which also includes the manufacturer ID.

I tried appending data to the same buffer before it gets populated but when i add the custom data, the device throws error stating 'Failed to set advertising data: -22' and 'Failed to create extended advertisement: -22'

I add the following snippet to the ext_adv_populate() function -

ret = bt_mgmt_manufacturer_uuid_populate(&uuid_buf, CONFIG_BT_DEVICE_MANUFACTURER_ID);
if (ret) {
	LOG_ERR("Failed to add adv data with manufacturer ID: %d", ret);
	return ret;
}

/* USER CODE */

NET_BUF_SIMPLE_DEFINE_STATIC(str_buf, CONFIG_EXT_ADV_UUID_BUF_MAX);

ret = custom_name_populate(&str_buf);
if (ret) {
    LOG_ERR("Failed to add adv data with name", ret);
	return ret;
}

 ext_adv_buf[ext_adv_buf_cnt].type = BT_DATA_NAME_SHORTENED;
 ext_adv_buf[ext_adv_buf_cnt].data = str_buf.data;
 ext_adv_buf[ext_adv_buf_cnt].data_len = str_buf.len;
 ext_adv_buf_cnt++;
 
 /* USER CODE */
 
 ret = unicast_server_adv_populate(&ext_adv_buf[ext_adv_buf_cnt],
					  ext_adv_buf_size - ext_adv_buf_cnt);

Could you please shed some light into what is wrong in the implementation?

RE: BLE connection processing with nRF5340 Audio - 2

Amanda Hsieh — Thu, 13 Mar 2025 16:52:34 GMT

You can modify or replace that function if you don't want to check the advertising data for the matching device name.

RE: BLE connection processing with nRF5340 Audio - 2

SNJY — Wed, 12 Mar 2025 22:58:44 GMT

I tried adapting the exercise for the existing nrf5340 unicast_client example. I also referred to another discussion for an extended implementation.

While it might work seperately, i am not able to make it work with the unicast_client example.

I figured that instead of using the filter, the unicast client passed the peripheral device name in bt_mgmt_scan_start() which is eventually used to compare with any new device connection (in the device_name_check() function)

Do i need to disable/bypass this complete loop if i am trying to implement filters in the central device?

RE: BLE connection processing with nRF5340 Audio - 2

Amanda Hsieh — Tue, 11 Mar 2025 21:56:34 GMT

Check the Exercises in that course.

RE: BLE connection processing with nRF5340 Audio - 2

SNJY — Tue, 11 Mar 2025 17:26:39 GMT

Yes i am also looking into that, alternatively is there an example where this is applied?

RE: BLE connection processing with nRF5340 Audio - 2

Amanda Hsieh — Tue, 11 Mar 2025 17:24:38 GMT

I recommend checking out the Bluetooth Low Energy Fundamentals course, which covers these concepts in detail.

RE: BLE connection processing with nRF5340 Audio - 2

SNJY — Tue, 11 Mar 2025 16:32:48 GMT

Thanks,

After setting a static ID by CONFIG_BT_PRIVACY=n, the local address is retained over multiple connections as expected. I also want to provide the connection details for the central to the peripheral. (if we can store the ID on the other device)

Assuming that we have multiple such pairs, how do i bond these pairs.One way i learnt is that central can have an accept list to connect to known peripherals

Can you provide the right direction?

RE: BLE connection processing with nRF5340 Audio - 2

Amanda Hsieh — Tue, 11 Mar 2025 15:45:17 GMT

Hi,

[quote user=""]Is the above understanding true?[/quote]

That's correct.

[quote user=""]How is the ID retained in the peripheral?[/quote]

When using Resolvable Private Addresses (RPA) in Bluetooth LE, the device's identity is retained through the Identity Resolving Key (IRK), which is exchanged during the bonding process.

[quote user=""]Is it possible to setup a static ID for the central and let the perihperal always try connecting to it? If so, how?[/quote]

You can set CONFIG_BT_PRIVACY=n in the prj.conf.

Regards,
Amanda H.